Water Quality Evaluation, Spatial Distribution Characteristics, and Source Analysis of Pollutants in Wanquan River, China

Surface water quality assessment is an important component of environmental protection and sustainable development. In this study, 24 sampling sites were arranged in the Wanquan River area of Hainan Island, China, in 2021, and nine water quality indicators were measured. The water quality of the Wanquan River was assessed using the single factor pollution index method and the Nemerow pollution index method; the spatial distribution characteristics of pollutants were revealed, and the sources of pollution were further analyzed using factor analysis. The results show that the overall water quality of the Wanquan River basin is good, with the average values of all indicators meeting China’s Class III water quality standards. The results of the single factor pollution index method showed that 29% of the sampling sites were in the no pollution class, 38% in the slight pollution class, 25% in the light pollution class, and 8% in the moderate pollution class. The results of the Nemerow pollution index showed that 25% of the sampling sites were in the clean category, 17% in the cleaner category, 42% in the light category, and 17% in the moderate category. The results of the factor analysis show that agricultural activities and domestic sewage discharge are the main sources of pollution, with nitrogen and phosphorus being the most important factors affecting water quality. This paper proposes several measures to reduce water pollution in the Wanquan River, including improving agricultural activities, improving wastewater treatment, and strengthening environmental monitoring. The findings have practical implications for reducing water pollution in rivers and lakes and can provide a reference for policy decisions related to water resource management and environmental protection.